Probe tile for probing semiconductor wafer

ABSTRACT

A tile used to hold one or more probes for testing a semiconductor wafer. The tile has one or more sites for inserting one or more probes to test the semiconductor wafer. Each site has one or more holes. Each hole is coupled with a slot forming an angle. A probe is inserted into the file from a top of the tile through the hole and seated on the slot. The probe has a probe tip. The probe fip is in contact with the semiconductor wafer at one end of the slot at a bottom of the file. The probe fip is aligned with an X and Y coordinates of a bond pad on the semiconductor wafer.

This application is a continuation-in-part of application Ser. No.09/021631 filed on Feb. 10, 1998.

FIELD OF THE INVENTION

This invention relates generally to semiconductor test equipment, andmore particularly, to a system and method for using a plurality of probetiles and probes for electrically probing a semiconductor wafer.

BACKGROUND OF THE INVENTION

The semiconductor industry has a need to access many electronic deviceson a semiconductor wafer. As the semiconductor industry grows anddevices become more complex, engineers and scientists require tools toaccess devices quickly and easily on a semiconductor wafer. Many wafertests take hours, days, or weeks to perform, and would more efficientlybe performed in parallel. Probe cards have been developed to probe longrows or areas of the wafer. However, these developments are still gearedto a short-term electrical tests and a limited temperature range.

Semiconductor wafer probing is typically performed with probe cardsbuilt using FR-4, polyamide or a similar material. Such cards typicallyuse an epoxy ring to hold tungsten probes in place. These types of probecards are generally designed for probing one device at a time on thewafer in a narrow temperature range. The larger vendors of these typesof probe cards are Cerprobe, Probe Technology, MJC Japan, and others.Probers, built by companies such as Electraglass and TEL, step the probecard across the wafer so the devices on the wafer can be electricallyprobed.

Ceramic versions of a typical probe card have been developed, howeverthese are limited to, and designed for, probing a single device. Otherceramic probe cards have been designed for probing a confined area of awafer at a narrow temperature range. These probe cards can bepermanently damaged and broken if driven into the wafer.

No method is currently known to probe multiple locations over a broadarea on a semiconductor wafer. The need to access several locations on asemiconductor wafer will increase as design rules shrink devicefeatures, the speed of devices increases, and device shipments continueto grow at high rates. Therefore, there is a need for a way to probemultiple locations on a semiconductor wafer. Further, there is a needfor a robust probe card which may probe a wafer at a wide temperaturerange without breaking.

SUMMARY OF THE INVENTION

In one embodiment of the present invention, a tile used to hold one ormore probes for testing a semiconductor wafer is disclosed. The tile hasone or more sites for inserting one or more probes to test thesemiconductor wafer. Each site has one or more holes. Each hole iscoupled with a slot forming an angle. A probe is inserted into the tilefrom a top of the tile through the hole and seated on the slot. Theprobe has a probe tip. The probe tip is in contact with thesemiconductor wafer at one end of the slot at a bottom of the tile. Theprobe tip is aligned with an X and Y coordinates of a bond pad on thesemiconductor wafer.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example by theaccompanying drawings, in which like references indicate similarelements and in which:

FIGS. 1A, 1B, 1C, 1D show a top, front, and side view, and bottom viewof a probe tile and probe platform compatible with the presentinvention;

FIG. 2A shows a ceramic tile, probe wire, and semiconductor wafer detailcompatible with the present invention;

FIG. 2B shows an exemplary probe and bond pad compatible with thepresent invention;

FIG. 3 shows an exploded view of a ceramic tile with tile bushingscompatible with the present invention;

FIG. 4A shows a milled self-aligning hole compatible with the presentinvention;

FIG. 4B illustrates an exemplary drawing of a plurality of drill holes,machined guides, and view hole compatible with the present invention;

FIG. 4C illustrates an exemplary close up top-down view of the view holeshowing the plurality of probes.

FIG. 5 shows a small square ceramic tile compatible with the presentinvention;

FIG. 6 shows a square ceramic tile compatible with the presentinvention;

FIG. 7 shows a large square ceramic tile compatible with the presentinvention;

FIG. 8 shows pie shaped ceramic tiles compatible with the presentinvention;

FIG. 9 shows a gear wheel compatible with the present invention.

FIG. 10A is an exemplary illustration of a bottom-up view of a tile withmultiple probes.

FIG. 10B is an exemplary illustration of a top-down view of the tileillustrated in FIG. 10A.

FIG. 11 is an exemplary illustration of one embodiment of a probe in thepresent invention.

FIGS. 12A, 12B and 12C illustrate one exemplary embodiment of a tilemounted on a PCB configuration used in a high temperature environment.

FIGS. 13A, 13B and 13C illustrate one exemplary embodiment of a tileconfiguration used in an environment where high temperature is notrequired.

FIGS. 14A, 14B and 14C illustrate one exemplary embodiment of a tileconfiguration used in an environment where high temperature is notrequired.

FIGS. 15A, 15B and 15C illustrate one exemplary embodiment of a tileconfiguration used in an environment where high temperature is notrequired.

DETAILED DESCRIPTION

In the following description of a preferred embodiment, reference ismade to the accompanying drawings, which form a part hereof, and inwhich is shown by way of illustration a specific embodiment in which theinvention may be practiced. It is to be understood that otherembodiments may be utilized and structural changes may be made withoutdeparting from the scope of the present invention.

For purposes of explanation, numerous specific details are set forth inthe following description in order to provide a thorough understandingof the present invention. However, it will be evident to one of ordinaryskill in the art that the present invention may be practiced withoutsome of these specific details. In other instances, well-knownstructures and devices are shown in block diagram form in order tofacilitate description.

The present invention significantly decreases the amount of timerequired to probe multiple dies on a semiconductor wafer. The presentinvention is useful in assisting the determination of semiconductorreliability, and assisting device manufacturers with device development,research and development, process development, yield enhancement, devicefailure analysis and device testing.

The present invention provides a probe tile and probe platform forelectrically probing many semiconductor wafer bond pads over a broadarea of the semiconductor wafer. Nine ceramic tiles are configured in aflat three by three matrix, and are held in place by a probing platform.The tiles preferably have the dimensions of 1.8 inches (45.7 mm) long,by 1.8 inches (45.7 mm) wide, by 0.125 inches (3.2 mm) high, but it willbe recognized by one of ordinary skill in the art that other tiledimensions, for example four inch tiles or six inch tiles, may be usedwithout loss of generality. Each file may be moved independently in an Xand Y direction. FIG. 1A illustrated one embodiment of the probeplatform having three side control knobs 108 to move a tile in the Xdirection and three front controls knobs 107 to move a file in the Ydirection. The front control knobs 107 are attached to fronttransmission shafts 109, and the side control knobs 108 are attached toside transmission shafts 111. The front and side transmission shafts 109and 111 slide back and forth into three ball detent positions 102. Theball detent positions 102 determine which file is engaged and can bemanipulated. The front and side control knobs 107 and 108 and balldetent positions 102 are preferably operated by hand, but may also beattached to a motor or other movement mechanism for automaticpositioning and selecting of the semiconductor wafers and dies duringtesting. It will be recognized by one of ordinary skill in the art thatthe number of ceramic files, control knobs, and transmission shafts maybe increased or decreased without loss of generality. For example, thepresent invention could be configured with sixteen tiles having fourcontrol knobs and transmission shafts on the side of the platform andfour control knobs and transmission shafts on the front of the platform.

A preferred embodiment of the present invention is shown in FIGS. 1A,1B, and 1C. A round front control knob 107 is connected to a fronttransmission shaft 109, and a round side control knob 108 is connectedto a side transmission shaft 111. The front control knob 107 or the sidecontrol knob 108 permits the user to transmit rotational power to atransmission shaft. There are three side control knobs 108 and threeside transmission shafts 111 on the right side of the probing platform,and there are three front control knobs 107 and three front transmissionshafts 109 on the front of the probing platform.

A front transmission shaft 109 or a side transmission shaft 111 isconnected to three gears 101. The front transmission shaft 109 or theside transmission shaft 111 transmits rotational power to the connectedgears 101. Each round front control knob 107 and front transmissionshaft 109 or each round side control knob 108 and side transmissionshaft 111 is connected to a round detent strike 123. The detent strike123, together with a ball plunger 135, permits the user to engage onlyone gear at a time by sliding it back and forth in three detentpositions 102. A gear 101 is connected to a front transmission shaft 109or a side transmission shaft 111. The gear 101 transmits rotationalinput from the front transmission shaft 109 or the side transmissionshaft 111 to a stub shaft gear 103.

The stub shaft gear 103 is connected to a stub shaft 113. The stub shaftgear 103 transmits rotational input from the gears to the stub shaft113. As the stub shaft 113 rotates, threads move the X-transfer block119 back and forth in the X direction, or the Y-transfer block 121 backand forth in the Y direction.

The stub shaft 113 and the front transmission shaft 109 or the sidetransmission shaft 111 are held in place by a square bearing 117. Thereare preferably sixteen square bearings 117, one located at each cornerof the three by three matrix.

A ceramic tile 125 is fastened to the X-transfer block 119 and theY-transfer block 121 by a round tile bushing 105, and a flat head screw.There are preferably three bushings 105 and three screws used on eachtile 125. FIG. 1D illustrates an exemplary bottom view of the platform,showing the square bearings 117, the bushing 105, and the tile 125. Thesquare bearings 117 are preferably held in place by a mounting plate115. The mounting plate 115 is held in place by front standoff 127, backstandoff 129, left standoff 131, and right standoff 133. The standoffsattach to a base plate 137.

A removable clear glass plate 139 is present on the platform. Not shownis a removable opaque cover, roughly conforming to the shape of themounting plate 115, that may be placed over the glass plate 139 duringlight sensitive experiments. Also not shown are vacuum couplings,attached to base plate 137, which provide a vacuum to retain the baseplate 137 to a probe station.

The base plate 137, as well as certain other portions of the platform,are preferably constructed from stainless steel throughout to permittesting in high temperatures and to provide a thermal coefficient ofexpansion equal in all parts of the platform.

As shown in FIG. 2A, a ceramic file 201 holds electrochemically etchedtungsten probe tips 203 to permit semiconductor wafer testing over awide temperature range. The probes 205 are self-aligning and preferablyhave a high density of 0.020 inch linear pitch. As shown in FIG. 2, theprobes configured to fit the tile pattern of the probe platform. Thetungsten probes 205 are preferably set into drilled holes in eachceramic tile with high temperature ceramic epoxy, but it will berecognized by one of ordinary skill in the art that the probes may beattached in other ways and by other means without loss of generality. Itwill also be recognized that while the probes 205 may be made oftungsten, they may also be made of electrically conductive material,such as beryllium copper (BeCu), which does not substantially deform andremains electrically conductive over a wide range of temperatures. FIG.2B illustrates an exemplary drawing of the probe 205 and the bond pad202. As shown in FIG. 3, a ceramic tile 301 includes special mountingholes 303 and guides 305 to allow their connection to the probeplatform. Bushings 307 are used to attach the tile to the probeplatform.

As shown in FIG. 4A, the tungsten probes are typically placed inprecision machined guides 403 and drill holes 405 in the ceramic tile401 to self align the probes with bond pads on the semiconductor wafer.FIG. 4B illustrates an exemplary drawing of a plurality of drill holes405, machined guides 403, and view hole 409. The number of probes on asemiconductor wafer is primarily dependent upon the semiconductor wafertype and the number of electrical contacts. There may be as little asone probe, or else there may be many probes per semiconductor wafer.Drilled holes 405 and machined guides 403 in the ceramic tiles 401 areprovided to accommodate the tungsten probes. FIG. 4C illustrates anexemplary close up top down view of the view hole showing the pluralityof probes. Through the view hole 409, the plurality of probes 412 andthe bond pads 415 can be seen.

Referring back to FIG. 2A, the semiconductor wafer 207 rests on asemiconductor wafer chuck below the ceramic tile 201 which enables thetungsten probes 205 to then make electrical contact with the bond pad ofthe semiconductor wafer 207.

View holes 209 may optionally be created through some or all of theceramic tiles to permit viewing of the semiconductor wafer 207 ifrequired by certain applications. The low profile of the ceramic tiles201 enables a dry nitrogen environment near the semiconductor wafer 207,and the optionally present view holes 209 enable the ability to view adevice under test (DUT) without breaking the nitrogen environment. Tomaintain a dry nitrogen environment, a clear glass plate is placed inthe platform, forming a seal with the platform. The seal may be a looseseal if a positive pressure nitrogen environment is maintained.Alternatively, the seal may be gas-tight if a non-positive pressurenitrogen environment is used.

Alternative embodiments of ceramic tiles which may be used with thepresent invention are shown in FIGS. 5, 6, 7, and 8. As shown in FIG. 5,a preferred embodiment of the file may be a 62 mm×62 mm square file 501having three retainer slots 503, one each of the retainer slots 503being located in three of the four comers of the tile. As shown in FIG.6, an alternative embodiment of the tile may be a 110 mm×110 mm squarefile 601 having four retainer slots 603, one each of the retainer slots603 being located along each edge of the tile and substantially centeredalong each side. As shown in FIG. 7, an alternative embodiment of thefile may be a 160 mm×160 mm square file 701 having four retainer slots703, one each of the retainer slots 703 being located along each edge ofthe file and substantially off-centered along each side. As shown inFIG. 8, another alterative embodiment of the tile may be pie shapedfiles 801 with a combined radius of 200 mm square, each tile havingthree retainer slots 803, one each of the retainer slots 803 beinglocated in each of the three corners of a file 801. It will berecognized by one of ordinary skill in the art that the dimensions of atile, and the number and placement of retainer slots on a file, may varyfrom the embodiments described above without loss of generality.

A preferred gear wheel 901 is shown in FIG. 9, showing a side view and afront view. A gear wheel 901 is attached to the front transmissionshafts 109 and to the side transmission shafts 111, as shown by gears101 in FIG. 1. The gear wheels engage each other and transmit rotationalpower from a front transmission shaft 109 or a side transmission shaft111 to move a probe file in the direction of either the X direction or Ydirection.

The tile and probe platform discussed above together form the probe cardto electrically probe many semiconductor wafer bond pads over a broadarea of a semiconductor wafer. The platform positions the tile over thesemiconductor wafer. The tile can be replaced without replacing theplatform. Furthermore, tiles of different sizes can be used with theplatform to accommodate change in devices and wafer requirements. Thisis advantageous over the existing probe card technology (e.g., epoxyring probe cards, ceramic blade probe cards, etc.). For example, theprobes on the epoxy ring probe card are epoxyed in place on a substrate,and the ceramic blades on the ceramic probe cards are soldered in place.The tiles in the present invention are constructed of a rigid ceramic toprovide thermal, mechanical and electrical characteristics to allow thetiles to perform in high temperature over a long period of time. Thefiles and the stainless steel probe platform allow the probe card tooperate in a wide temperature range (e.g., −65 degress Celcius to 300degrees Celcius) or at low current leakages at one site or at multiplesites. This is advantageous over the existing probe card technology,which normally operates in a narrower temperature range.

In one embodiment, the tile described above may be mounted on a printedcircuit board (PCB) to test the wafer. In this case, the tile is held inplace by the PCB instead of by the platform. The tile can be can be indifferent sizes and thickness. For example, when mounted on the PCB, thetile can be round, square, rectangular or hexagonal, from 30 m.m. indiameter to 210 m.m. in diameter. The thickness varies (e.g., 3 m.m. to9 m.m.) depending on the stiffness required. One or more probes aremounted on the tile. The probes are used to electrically probe multipledevices or multiple sites depending on the layout of the semiconductorwafer to be probed.

The probes are placed into the tile according to the bond pad pattern.As discussed above, the tile is designed with slots (or grooves) anddrilled holes to accommodate the probes. The slot and drilled holes arefabricated into the tile in a manner that allows the seated probe to bealigned with the X and Y coordinates of the bond pad on thesemiconductor wafer. The slot forces a specific X, Y and Z orientationof the probe. In one embodiment, the slot and the drilled hole form a 90degrees angle (e.g., “L” shape) to help the probe self align with thebond pad. Each probe is inserted into the drilled hole and seats itselfinto the slot.

FIG. 10A is an exemplary illustration of a bottom-up view of a tile withmultiple probes. In this example, the probes are mounted in nine sitesacross the tile 1013. Also illustrated in FIG. 10A are the retainerslots 1010, the probes 1012 at each of the nine locations and the viewhole 1011. Each of the probes 1012 can be removed from its slot anddrilled hole without disturbing adjacent probes. The number of sites onthe tile, the number of probes accommodated by the tile, the positionsof the probes, and the size of the tile vary depending on the area ofcoverage and the number of sites to be probed.

The probes may be connected to wires to interface with a test system.The probes may also be connected to the PCB using a permanent solderconnection or a spring contact pin receptacle. The spring contactpermits quick replacement of any damaged probes. FIG. 10B is anexemplary illustration of a top-down view of the tile illustrated inFIG. 10A. The tile is shown without the PCB or the wire interface.

FIG. 11 is an exemplary illustration of one embodiment of a probe in thepresent invention. The probe 1105 is FIG. 11 comprises a probe tip 1110,a beam or cantilever 1115, and the vertical shank 1120 that goes throughthe tile. The probe tip 1110 is the bent down end of the probe 1105 thattouches the bond pad. When the probe tip 1110 is damaged or worn out theentire probe 1105 is replaced. The probe 1105 is different from theprobe 205 in FIG. 2A and FIG. 2B. The vertical shank of the probe 205 inFIG. 2A and FIG. 2B is straight, whereas the vertical shank 1120 of theprobe 1105 in FIG. 11 has a kink at location 1125. The kink isadvantageous because it provides a spring action to the probe 1105 tofirmly retain the probe 1105 in the drilled hole and slot of the tile.

FIGS. 12A, 12B and 12C illustrate one exemplary embodiment of a tilemounted on a PCB configuration used in a high temperature environment.FIG. 12A illustrates a top view, FIG. 12B illustrates a side view, andFIG. 12C illustrates a bottom view. The tile 1204 is mounted onto thePCB 1202. A stand off and thermal insulating material 1203 separates thetile 1204 from the PCB 1202. The insulating material 1203 allows thetile 1204 to be used at high temperatures without causing deteriorationof the PCB 1202 that has a lower operating temperature. The probe 1201is attached to the PCB 1202 using a spring contact pin receptacle 1208.The probe tip of the probe 1201 is in contact with the semiconductorwafer bond pad 1206 to probe the semiconductor wafer 1205. The space1210 represents the opening in the view hole.

FIGS. 13A, 13B and 13C illustrate one exemplary embodiment of a tileconfiguration used in an environment where high temperature is notrequired. FIG. 13A illustrates a top view, FIG. 13B illustrates a sideview, and FIG. 13C illustrates a bottom view. The tile 1304 is mountedonto the PCB 1302. There is no stand off thermal insulating materialbetween the tile 1304 and the PCB 1302 because this embodiment is notused in high temperature environments. The probe 1301 is attached to thePCB 1302 using a spring contact pin receptacle 1308. The probe tip ofthe probe 1301 is in contact with the semiconductor wafer bond pad 1306to probe the semiconductor wafer 1305.

FIGS. 14A, 14B and 14C illustrate one exemplary embodiment of a tileconfiguration used in an environment where high temperature is notrequired. FIG. 14A illustrates a top view, FIG. 14B illustrates a sideview, and FIG. 14C illustrates a bottom view. The tile 1404 is mountedonto the PCB 1402. In this embodiment, a wire guide is used to providevarious probe patterns by swapping the tiles on one PCB. There is nostand off thermal insulating material between the tile 1504 and the PCB1502 because this embodiment is not used in high temperatureenvironments. The probe 1401 is attached to the PCB 1402 using a springcontact pin receptacle 1408. The probe tip of the probe 1401 is incontact with the semiconductor wafer bond pad 1406 to probe thesemiconductor wafer 1405. The wire guide 1407 is made of an insulatingmaterial.

FIGS. 15A, 15B and 15C illustrate one exemplary embodiment of a tileconfiguration used in an environment where high temperature is notrequired. FIG. 15A illustrates a top view, FIG. 15B illustrates a sideview, and FIG. 15C illustrates a bottom view. In this embodiment, eachprobe 1501 is attached to an insulated wire 1512. There is no springcontact pin receptacle when quick removal and replacement of the probe1501 is not required. Furthermore, there is no stand off thermalinsulating material used with the tile 1504 because this embodiment isnot used in high temperature environments. The probe 1501 is attached tothe tile 1504 semi permanently with epoxy. The probe tip of the probe1501 is in contact with the semiconductor wafer bond pad 1506 to probethe semiconductor wafer 1505.

Thus what has been described is a tile and a probe used for electricallyconductive probing of semiconductor wafer. The tile is specificallydesigned with slots and drilled holes to accommodate a probe. The probecan be inserted into any drilled holes in the tile. Each probe may bedesigned with a kink to help keep the probe seated in the tile. Whenquick removal is necessary, the probe can be held in place by usingspring contact pin receptacle. The probe is fabricated in an angleincluding a kink to act as a spring to retain the probe in the drilledhole of the tile. Typically, the probe described above is made oftungsten. However, the probe can also be fabricated using otherconductive alloy or similar materials. In addition, although theinvention describes probing the semiconductor wafer, one skilled in theart would recognize that the invention may also be used to test amulti-chip module and other substrates.

From the above description and drawings, it will be understood by thoseof ordinary skill in the art that the particular embodiments shown anddescribed are for purposes of illustration only and are not intended tolimit the scope of the invention. Those of ordinary skill in the artwill recognize that the invention may be embodied in other specificforms without departing from its spirit or essential characteristics.References to details of particular embodiments are not intended tolimit the scope of the claims.

1. In a semiconductor wafer testing system where one or more probes areused to test a semiconductor wafer, a tile is used to hold the one ormore probes for making contacts with the semiconductor wafer, the tilecomprising: wafer, each site having one or more holes, each hole coupledwith a slot forming an angle, wherein a probe is inserted into the tilefrom a top of the tile through the hole and seated on the slot, theprobe having a probe tip in contact with the semiconductor wafer at oneend of the slot at a bottom of the tile, wherein the probe tip isaligned with an X and Y coordinates of a bond pad on the semiconductorwafer. 2-16. (canceled)